A Model for Correlated Internal Motions and Deuteron Spin Relaxation in Liquid Crystals
Measurements of deuterium spin-lattice relaxation times allow the determination of spectral densities of motion J1 (w) and J2 (2w) for various deuterated sites in liquid crystals. The effects of correlated internal rotations in the pentyl chain of 5CB on the spectral densities of the chain deuterons are examined using the master equation method. Transitions among allowed chain configurations in a diamond lattice are described by a rate matrix in the master equation. The equilibrium probability of each configuration is calculated by the Emsley-Luckhurst approach. Both J1 (w) and J2 (2w) are predicted to depend on frequency, with the frequency dependence in J2 (2w) being weaker.
PACS number61.30.-v 33.25.—j.